Homogeneous catalysis is an important step in the synthesis of numerous commercially useful compounds. For example, catalytic reactions are employed to reduce groups such as alkenes, aldehydes and nitriles to alkanes, alcohols and amines, respectively. Such catalytic reactions often use salts and/or complexes of a Group VIII metal, such as rhodium, platinum, palladium or cobalt, as the homogeneous catalyst.
A catalyst is a substance which increases the rate of a chemical reaction without being consumed in the reaction. Since the catalyst is not consumed, it is economically desirable to recover the catalyst for further use. This is especially true for catalysts containing exotic and expensive metals such as rhodium. Furthermore, it is also desirable to recover the catalyst in an active form, substantially ready for immediate re-use, as this eliminates the expense associated with re-activating the catalyst.
An object of the present invention is to provide a process by which homogeneous metallic catalysts may be recovered in active form suitable for immediate re-use. The present process accomplishes such recovery in high yield, while utilizing extremely inexpensive materials. Thus, the present process provides an economically attractive route for recovering homogeneous metallic catalysts from catalytic reaction mixtures once the catalytic reaction has been completed.